Patent Document 1 proposes a retroreflector in which reflective elements (light reflecting units) each of which is formed by combining a pair of corner reflecting surfaces that come into contact with each other at a dihedral angle of substantially 90 degrees and a perpendicular reflecting surface formed on a partition wall orthogonally intersecting with the corner reflecting surfaces are arranged in an orderly manner. Patent Document 2 proposes a stereoscopic-image display device in which a half mirror is additionally incorporated with a retroreflector.
Patent Document 3 proposes an optical image-formation device in which first and second optical control panels formed by arranging belt-shaped planar light-reflecting portions perpendicularly to a surface on one side inside a transparent flat plate are used and in which the first and second optical control panels are disposed so that the planar light-reflecting portions of the first and second optical control panels orthogonally intersect with each other, and the optical image-formation device is capable of forming an image of an object placed on one side as a real image at a symmetrical position.